Let's review what the IPCC has to say about tornadoes (IPCC 4AR WG1 Ch3 FAQ3.3 p308):

Observational evidence for changes in small-scale severe weather phenomena (such as tornadoes, hail and thunderstorms) is mostly local and too scattered to draw general conclusions; increases in many areas arise because of increased public awareness and improved efforts to collect reports of these phenomena.

They clarify this, a little, in section 3.8.4.2, again stressing that the question of tornadoes depends on local measurements, which are too variable to use for any global conclusions. But basically they punt on the issue. Fair enough.

More extreme and violent climate is a direct consequence of human-caused climate change (whether or not we can determine if these particular tornado outbreaks were caused or worsened by climate change).

The extreme nature of the ongoing severe weather is well described by Jeff Masters on his Weather Blog. The 3-day total of preliminary tornado reports from this week's outbreak is nearing 300, close to the 323 preliminary tornado reports logged during the massive April 14 - 16 tornado outbreak. That outbreak has 155 confirmed tornadoes so far, making it the largest April tornado outbreak on record.

You don't have to look very far to disprove this -- in fact, you don't even have to look farther than the Drudge Report, which today links to this story:

TuscaloosaNews.com
5 P.M. UPDATE: Hundreds treated at DCH
"The loss of life is the greatest from an outbreak of U.S. tornadoes since April 1974, when 329 people were killed by a storm that swept across 13 Southern and Midwestern states."

When are activists going to learn that they will never make their case by falsifying the science, and that, in fact, they only harm their cause when they do so? You cannot draw conclusions about climate based on weather. You can only do it via long-term (decadal or more) statistics.

Please tattoo this on your foreheads, so you don't ruin this for those of us trying to communicate actual, real science, with all its inconvenient unknowns and uncertainties.

14 comments:

So let's see, lost lives and number of tornadoes have a one-to-one correspondence? Gettin' sloppy, David. Being entirely dependent on where and to an extent when the tornadoes touch down, loss of life has a rather loose relationship to the severity of the outbreak.

Also, bear in mind that the science in the AR4 is now no less than five years old. Stuff has happened since.

"A team of researchers under the auspices of the World Meteorological Organization has published a new review paper in Nature Geoscience (PDF) updating consensus perspectives published in 1998 and 2006. The author team includes prominent scientists from either side of the "hurricane wars" of 2005-2006: Thomas R. Knutson, John L. McBride, Johnny Chan, Kerry Emanuel, Greg Holland, Chris Landsea, Isaac Held, James P. Kossin, A. K. Srivastava and Masato Sugi."

"The latest WMO statement should indicate definitively (and once again) that it is scientifically untenable to associate trends (i.e., in the past) in hurricane activity or damage to anthropogenic causes."

So where is the storm data trend that supports your position?

Please explain the physical theory that supports your position (I explained mine which you didn't challenge).

So all storms are tropical cyclones, charlesH? You really don't want to know what the IPCC says about storminess, do you? Even for TCs, the expectation is that they will get stronger if not more frequent in the short term.

Re the delta T, bear in mind that as the tropics heat up the flux toward the poles will increase regardless. In the short term, while we still have ice sheets, there will be more than enough delta T to drive stronger storms. This is an observed effect, BTW, not just theory.

The average kinetic energy of the molecules of an ideal gas is proportional to the temperature T. So is the average deviation of molecular energy from the average energy--that is, the distribution of energies widens. The entropy varies as ln(T).

Just look at a pot of water on the stove burner. Or ask why we get thunderstorms on hot days but rarely on cold days.

"Thunderstorms can generally form and develop in any geographic location, perhaps most frequently within areas located at mid-latitude when warm moist air collides with cooler air.[2]"

"Thunderstorms are responsible for the development and formation of many severe weather phenomena. Thunderstorms, and the phenomena that occur along with them, pose great hazards to populations and landscapes. Damage that results from thunderstorms is mainly inflicted by downburst winds, large hailstones, and flash flooding caused by heavy precipitation. Stronger thunderstorm cells are capable of producing tornadoes and waterspouts."

http://en.wikipedia.org/wiki/Thunderstorm

And in fact we see the most severe weather (thunderstorms, hurricanes, tornadoes) occurring in the mid latitudes where temp differences are greatest not in the hottest tropical areas.

"The average kinetic energy of the molecules of an ideal gas is proportional to the temperature T. So is the average deviation of molecular energy from the average energy--that is, the distribution of energies widens. The entropy varies as ln(T). "

Well ok but the gas is well mixed with the "hot" and "cold" molecules thus no energy to drive a heat engine (like a storm). If one could find a way to separate the hot and cold molecules without expending energy you could extract work from such a gas.